Relay system



'April 18, 1939. A. H. LAMB RELAY sysm nu Filed Nov. 23, 1936 Patented Apr. 18, 1939 PATENT OFFICE RELAY SYSTEM Anthony H. Lamb, Elizabeth, N. J., assignor to Weston Electrical Instrument Corporation, Newark, N. 1., a corporation of New Jersey Application November 23, 1936, Serial No. 112,423 I 11 Claims.

This invention relates to relay systems and particularly to relay systems of the type which includes an instrument type relay controlling the operation of a reversible motor or equivalent devices for effecting changes in a positive or negative sense.

An object of the invention is to provide a relay system including a reversible control element and a sensitive relay for actuating the control elelO ment, these devices being operatively connected through a circuit that includes mechanism for limiting each control operation to not more than a limited period or control pulse. An object is to provide a relay system including a sensitive l5 relay for closing alternate circuits which each include an auxiliary relay for closing a holding circuit and one energizing circuit of a reversible motor, and a pulsing device for limiting the operation of the reversible motor to a comparatively short period or pulse. An object of the invention is to provide relay systems of the type stated in which the pulsing device opens a switch in the circuit of the auxiliary relays, thereby de energizing the same to stop the motor, and then closes the switch to permit a subsequent energization of the auxiliary relays by the sensitive relay. More specifically, objects are to provide relay systems of the type stated in which the pulsing device is actuated by the reversible ergized by the sensitive relay.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which:

Fig. 1 is a circuit diagram of a relay system embodying the invention;

Fig. 2 is a fragmentary circuit diagram of a modified arrangement of the portion of the Fig. 1 system at the right of line A--A, Fig. 1;

Fig. 3 is a vertical section through the double pulsing device shown in Fig. 2; and

Fig. 4 is a fragmentary circuit diagram illustrating a thermal type of pulsing device.

In the Fig. 1 diagram, the essential circuits for the fiow of current to the reversible control device are shown in heavy line, and other circuits are shown in light line. I

The primary or instrument relay is indicated diagrammatically by the moving coil I of an electrical measuring instrument, the coil carrying a pointer 2 that has a rider 3 of magnetic material for cooperation with a pair of stationary contacts I, 4' in the form of small permanent magnets. A pusher" system for separating the motor or by an independent motor that is enmagnetic rider from the magnet contacts is shown as a pair of pivoted arms 5, 5 that are moved towards each other by the solenoid 6. Sensitive instrument relays of this type are described in detail and claimed in my copending application Ser. No, 6,891, filed Feb. 1.6, 1935, now Patent No. 2,062,915, granted Dec. 1, 1936.

The control device I to which the moving coil is connected will depend upon the particular quantity or factor that is to be maintained at some desired value by the relay system. The device may be a thermocouple in the case of temperature control, the line or a resistor in the line in the case oi. the control of voltage to a load circuit, a photocell in the case of illumination or smoke control, or the device I may be one of these or other variation producing devices in other types of control, recording and/or alarm systems.

A source of current is connected between a pair of terminals 8, and one terminal is connected to the pointer 2 of the instrument relay by a lead 9. The relay contacts 4, 4' are connected to the solenoids III, Ill 01. auxiliary relays by leads I], II, respectively, and a common lead I2 extends from the solenoids to a contact l3 of a pulse controller or pulsing device. The pulsing device is shown as a multi-lobed cam wheel it having undercut teeth which permit the contact to lose contact with the wheel momentarily as the wheel is given a step-by-step rotation in counter-clockwise direction by the pawl I5 carried by armature i6 01 the solenoid. A contact 18 which bears continuously on the toothed contact wheel I4 is connected to the other terminal 8 by a lead 19. A spring 20 draws the contact l3 towards the wheel I4 and one of the described circuits (either through solenoid ill or solenoid ill) is therefore completed between the terminals ll when the pointer engages one of the relay contacts.

Each auxiliary relay controls two normally open switches 2|, 22 and 2|, 22', respectively, that have contact arms connected to one terminal 0- of the power source by a lead 2'. The switches 21, 2| are holding switches for the solenoids l0 and Ill, and their contact points are connected to leads II, II, respectively. The contact points of switches 22, 22' are connected to circuit elements 23, 23', respectively, of a re- 0 versible control device 24. The common return 25 for the alternatively energized circuit elements 2!, 23' may be connected either to the contact am It or the pulsing device or directly to -the lead is from the second terminal I of u the power source. As shown in Fig. 1, the lead 28 extends to a switch arm 28 that may be engaged with a contact of the lead 21 to the contact strip I! or a jumper 28 to the lead IS.

The circuit elements 22, 22 may be the di-' rect" and reverse field windings when the control device 24 is a motor for adjusting a tap along a resistance, for actuating valves or for driving other forms of regulating apparatus in opposite directions. The circuit elements 22, 22' may be electromagnets for shifting a regulating element between alternative control positions, or the circuit elements may be visual or audible signal devices in the case of an alarm circuit. The exact design and the operating characteristics of the alternative or reversible control device 24 may be varied at will in accordance with particular type oi automatic regulator or alarm that is desired.

A divided resistor '29 is shunted across the circuit elements 28, 22' oi the control device 24, and leads 20, 2| extend from the midpoint of the resistor to the solenoid 8 of the pusher arm system and to the solenoid ll of the pulsing device. The circuits for these solenoids are completed to the switch arm 28 by leads 22, 22, respectively, and a common lead 24.

The relay system operates in the following manner when, as illustrated, the switch arm 28 is closed on the jumper 28. The pointer 2 of the instrument relay is displaced in accordance with variations in the output of the unit I which,

for convenience of description, will be assumed to be a thermocouple in a space that is to be maintained at somepredetermined temperature. A drop in temperature will carry the pointer 2 adjacent a magnet contact, said contact 4, and magnetic attraction draws the rider 8 firmly against contact 4. This completes a circuit through the solenoid III as follows: from upper terminal 8, lead 9, pointer 2 and contact 4, lead H, the solenoid l0, lead l2, contact arm i2, cam wheel |4, contact arm l8, and lead it to the other terminal 8. Auxiliary relay switches 2|, 22 are thereby closed; the switch 2| completing a holding circuit for solenoid l0, and the switch 22 connecting lead 9 to the coil or element 22 of the reversible device 24. Current flow is thereby established through coil 22 since the lead 28, switch 28, jumper 28 and lead l8 complete the circuit back to the terminal 8. Current flow is also established through the upper section of resistor 29 to the resetting solenoid 8 and to the pulsing solenoid i1, through leads 2844, inclusive.

Energization of solenoid 6 causes pusher arm 5 to separate the pointer 2 from magnet contact 4, but the auxiliary relay is still energized through the holding switch 2|. Energization of solenoid results in a turning of the cam wheel I4 counter-clockwise and the auxiliary relay circuit is momentarils broken as the contact arm l3 of the pulsing device drops from one tooth to. the next. Switches 2| and 22 drop open at the momentary interruption of this circuit, thus opening the holding circuit oi. solenoid l8 and the circuit to coil 22 of the reversible device 24. The entire system is thus reset for another cycle of operations.

In the.assumed case oi a temperature control, the reversible control device 24 will actuate a variable resistance or a valve to increase the heating effect when the coil 22 is energized. If the temperature is still too low when the pusher arm 5 returns to normal position upon the opendescribed operations are repeated. A rise in temperature results in an engagement of contacts 2, 4' 01' primary relay, thus energizing solenoid ID to close switch 22' oi the coil 22' oi the reversible device 24. This results in an adjustment of the heat control element (resistance or valve) in the reverse sense to decrease the heat pp ywhen the switch arm 28 is closed on lead 21, the opening of they main circuit at the pulsing device interrupts the current supply to the auxiliary relays, the reversing device 24 and the solenoids of the pulsing and pusher device. This direct opening 0! the circuit of the reversible device 24 by the pulsing device provides a substantially shorter control cycle than is obtained in the other position of switch arm 28, particularly when the auxiliary relays I8, ID are designed for slow opening.

The above description refers to control operations but it will be apparent that the device 24 may be merely an alarm device in which the elements or coils 22, 22' actuate distinctive signals.

The pulsing device may be actuated by the reversible device 24, and one construction oi this type is illustrated in Figs. 2 and 3. The device 24 comprises a motor having an armature 28 that turns in different directions in accordance with the particular field winding 22 or 22' which is energized. The armature is connected through reduction gearing 28 to a control shaft 21 having a threaded end for displacing a control rod 28. A pair of contact wheels Ila, |4b are mounted on shaft 28 that is axially alined with and insulated from the shaft 27, the lobes of the wheels extending in opposite directions and the wheels being connected to the shaft by oppositely arranged one-way clutches 48 of known type for the counter-clockwise rotation of wheel I44 and the clockwise rotation of wheel |4b. Contact arms I211, I212 engage the respective wheels to form a pair of switches that are in series between the lead |9 from a source terminal 8 and the junction of the motor return 28' and the auxiliary solenoids return i2.

If the shafts 21, 28 rotate clockwise upon the energization of field winding 22, the wheel I40 0! the pulsing device remains stationary and the wheel lib rotates with shaft 28 to open the motor and auxiliary relay circuits when contact arm |2b drops from the end of one cam lobe. The system is thus reset for the next cycle 0! operations.

As shown in Fig. 4, the pulsing device may be a thermal switch having a bimetallic strip 4| that is deflected from normal closed circuit position by a heating coil 42 that is in series with the switch.

The duration of one control cycle or pulse is preferably so related to the speed of correction that the minimum desired correction will be effected in one cycle or pulse. Over-correction or hunting will be avoided when this relation exists and, for larger corrections, a number oi control actions take place in quick succession as the pulsing device restores the system to operative condition immediately after the termination of each control operation or pulse.

It will be apparent that the invention is not limited to the specific circuits and elements herein illustrated and described, and that various changes may be made without departing from the arms andapulsingdevicei'orlimltingtheenergixa of said auxiliary relay through said holding switch to notmore than a predetermined in- 2. A relay system comprising a primary relay having a contact arm movable between two fixed contacts, an auxiliary relay in circuit with each fixed contact, each auxiliary relay including a control circuit switch and a holding switch in shunt with the contact arm and the fixed contact oi the associated auxiliary relay, a reversible device having the operating elements thereof included in the respective control circuits, a normally closed pulsing switch for opening the circuits oi the auxiliary relays, said pulsing switch comprising two multilobed contact wheels with rcversely arranged lobes and contact strips bearing upon the edges of the respective wheels, and means operable by said reversible device for actuating said pulsing switch.

3. In a relay system, the combination with a primary relay having a contact arm carrying a magnetic rider and movable between two fixed magnetized contacts, a primary circuit having parallel portions each including the contact arm and one fixed contact, an auxiliary relay in each oi said parallel portions oi the primary circuit, each auxiliary relay including a holding switch for that relay and a control circuit switch, a reverslble device having a pair of alternatively operable elements in circuit with the respective control circuit switches, normally closed pulsing switch means in said primary circuit, means energiaed by the closing of said primary circuit by the primary relay for actuating the pulsing switch means to open and thereafter to closed position, and means energized by a closure oi the magnetic rider. upon 'either magnetized contact for separating the magnetic rider from the contact subsequent to the closing oi. the holding switch by the energized auxiliary relay.

4. In a relay system, the combination with a .primary relay having a contact arm movable between two fixed contacts, a primary circuit having parallel portions each including the contact arm and one fixed contact, an auxiliary relay in each oi said parallel portions of the primary circuit, each auxiliary relay including a holding switch for that relay and a control circuit switch, a reversible device having a pair of alternatively operable elements in circuit with the respective control circuit switches, normally closed pulsing switch means in said primary circuit, and means actuated by said reversing device at each operation thereof to open and thereai'ter to close said pulsing switch means.

5. In a relay system, the combination with a primary relay having a contact arm movable between two fixed contacts, a primary circuit having parallel portions each including the contact arm and one fixed contact, an auxiliary relay in each 01' said parallel portions of the primary circuit, each auxiliary relay including a holding switch for that relay and a control circuit switch, a reversible device having a pair oi alternatively her opsrabieelementsinclrouitwithtberespective control circuit switches. and normally closed pulsingswitchmeansinsaidprimarycircuit, saidpulsingswitchmeansincludingabimetallic actua strip and a heater thercior included insaidp ry'drouit,wherebyaclosureoithe primary circuitbytheprimaryrelayenergiles flieheatertoefiectanopeningoi'saidpulsing switchmeansbythebimetallic actuating mem- 6.Inarelay system, thecombination witha primary relay having a contact arm movable between two fixed contacts, a primary circuit having parallel portions each including the contactarmandonefixedcontacnanauxiliaryreiay in each oi said parallel portions of the primary circuit, each auxiliary relay including a holding switch for that relay and a control circuit switch, a reversible device having a pair of alternatively operable elements in circuit with the respective ;control circuit switches, normally closed pulsing switch means in said primary circuit, means energized by the closing oi said primary circuit by the primary relay for actuating the pulsing switch means to open and thereafter to closed position, and means for adjusting the length of the operating period of said reversible device upon an energization thereof: said last means including circuit elements and a switch for completing the circuit of the device in series with or alternatively in shunt with said pulsing switch means.

'7. In a relay system for operating a reversible motor in opposite directions in pulses of limited duration, the combination with a reversible motor having alternatively operable windings, and a control circuit having said windings in parallel branches thereof, a control circuit switch in each in said branches of the control circuit, normally closed pulsing switch means operable to interrupt current flow in a common portion of said control circuit, and means actuated by said reversible motor for opening and thereafter closing the pulsing switch.

8. In a relay system, the combination with a primary relay having a contact arm movable between a pair oi fixed contacts, and a reversible device having an alternatively operable winding, of a pair oi auxiliary self-holding relays in circuit with the respective fixed contacts, switches actuated by said self-holding relays for controlling current fiow alternatively in circuits that include the windings 01 said reversible device, and pulsing means for restricting the energize.- tion of said self-holding relays to a limited period; said pulsing means comprising normally closed switch means operable by said reversible motor.

9. A relay system as claimed in claim 8, in combination with manually operable switch means for completing the circuits of said windings of the reversible device alternatively in series with or in shunt to said pulsing device.

10. A relay system as claimed in claim 8 wherein said pulsing means comprises a pair of multi-lobed contact wheels having the lobes thereof reversely arranged, means including oneway driving connections for actuating said con-' 4 I a,1u,eu

ranged circuit elements in the primary relay circuit that includes said contact arm.

11. In a relay system, the combination with a primary relay having a contact arm movable between a pair of fixed contacts, and a reversible device having alternatively operable windings, of a pair of auxiliary self-holding relay: in circuit with the respective fixed contacts for controllingtheenergintlonoithewmdingsolnid reversible device, and pulsing means for restricting the tion of said self-holding relay: to a limited period; said puislng means comprin ing normally closed switch means and means including said reversible device for actuating the same.

ANTHONY H. mum. 

